Failing Fuel Pump Symptoms? Edit: Now With Data

[abuck99]

I kinda agree on the failing cat. 195k is about when the cats on my old Tundra gave up but they didn’t give me the drivability issues that I’m having now.

I do remember seeing a post here about the AI foam filter disintegrating, I haven’t done anything to address that and I’m not sure if @2001LC knew about that problem when he did all the work to this truck. Need to find the thread and have a look…

I did remove the intake tube to inspect and clean. While the MAF sensor obviously was dirty (tip in immediately improved after cleaning) the rest of the tube and throttle body wasn’t bad at all. The OEM filter was doing its job and keeping the clean side clean.

Overflow levels are good hot and cold, coolant looks good.

Thats good news the intake was clean and coolant level in the correct range.

If battery was disconnected when you cleaned the MAF, it takes several drive cycles for the ECU learn new parameters. If battery wasn’t disconnected- it may take a bit longer

 

[2001LC]

I kinda agree on the failing cat. 195k is about when the cats on my old Tundra gave up but they didn’t give me the drivability issues that I’m having now.

I do remember seeing a post here about the AI foam filter disintegrating, I haven’t done anything to address that and I’m not sure if @2001LC knew about that problem when he did all the work to this truck. Need to find the thread and have a look…

I did remove the intake tube to inspect and clean. While the MAF sensor obviously was dirty (tip in immediately improved after cleaning) the rest of the tube and throttle body wasn’t bad at all. The OEM filter was doing its job and keeping the clean side clean.

Overflow levels are good hot and cold, coolant looks good.

You're correct: S.A.I. mod wasn't done. The near term condition(s) that develop once filter gone, is with S.A.I and CAT. Whereas cylinder issue can devolve longer term, depending on dusty condition of roads traveled, as to how soon. It does take a long time. I would not expect BK 1 & 2 lean condition or a full bank misfire.

Great the coolant reservoir is function, which changing level is a good indicator.
But is is important to check 2 more coolant things.

1. Coolant level under the radiator cap.
2. Check Radiator fins for debris. This is so easy to see, even with #1 shield on.

It's also worth looking for muck/grim in fuel cap door area. This rig had it, and door was bent. At the time I though why did some pry out fuel cap door, and what was he putting in the tank "diesel". I now know the gas cap likely blew out bending the door and the muck/grim was fuel boiling issue. These past events may have damaged charcoal canister and other EVAP components. Although, no DTC or issues with of fumes ever reported, since engine was installed.

2007 LC, 194k miles. As far as I know the pump is original, filter was replaced about 65k miles ago. Currently on my way to Michigan.

Two days ago I drove from Boise to Ashton, ID. Drove perfectly fine the whole way until I missed my turn on a FS road and had to jab on the brakes fairly hard (not nearly hard enough to engage ABS though). I put in it reverse and notice the truck is really struggling to keep running and a few seconds later dies. I crank a few times but no start. I checked the fuel cap, no pressure escaping or fuel smell. I waited a few minutes and it fires up like nothing is wrong. I figure maybe it was because I had less than a 1/4 tank when I stabbed on the brakes and the pump grabbed some air? Doesn’t really make sense though…

No problems yesterday, filled up and did near 100 miles.

Today drove from Ashton to Grand Tetons and then another hour to find camp, also about 100 miles. When I arrived to camp I throw it into reverse and it starts to die again but this time I just shut it off. I check the cap again, nothing abnormal. I wait again, put the key to ON and listen for the fuel pump and can’t hear anything (I imagine these things are pretty silent though?). I crank it over and it starts right up and idles.

I’m not getting any idiot lights on the dash, unfortunately my new laptop won’t run Virtual Box so I haven’t hooked up Techstream.

Does this sound like a failing fuel pump or something else?

"jab on the brakes fairly hard" "reverse and it starts to die again" If moment had anything to do with stall. It "may" point to a loose ground or wire block.

No fuel press when gas cap removed. The cooling a few minutes then starting, does point to fuel point "kind of". What would is if was hot day and you had just Thottle back form running at a higher RPM.

Looks like the truck isn’t letting me off that easy. Drove fine after the pump install yesterday evening but this morning the check engine light and VSC lights are on. I can feel some surging going on when I hold the throttle at a steady cruise. Not sure what to make of that.

I’m going to continue on through Yellowstone today. Wish I still had Techstream up and running Is there anyone here around Northern Wyoming or the Black Hills that has TS and would be willing to help a brother out?

Condition/issue change for the worst, after a fuel pump install. First report of CEL.

 

[GTV]

Thats good news the intake was clean and coolant level in the correct range.

If battery was disconnected when you cleaned the MAF, it takes several drive cycles for the ECU learn new parameters. If battery wasn’t disconnected- it may take a bit longer

Oops, yeah I didn’t disconnect the battery. I’ve been through a few more tanks of 91 since then so maybe it’s good?

You correct: S.A.I. mod wasn't done. The near term condition(s) that develop once filter gone, is with S.A.I and CAT. Whereas cylinder issue can devolve longer term, depending on dusty condition of roads traveled, as to how soon. It does take a long time. I would not expect BK 1 & 2 lean condition or a full bank misfire.

Great the coolant reservoir is function, which changing level is a good indicator.
But is is important to check 2 more coolant things.

1. Coolant level under the radiator cap.
2. Check Radiator fins for debris. This is so easy to see, even with #1 shield on.

It's also worth looking for muck/grim in fuel cap door area. This rig had it, and door was bent. At the time I though why did some pry out fuel cap door, and what was he putting in the tank "diesel". I now know the gas cap likely blew out bending the door and the muck/grim was fuel boiling issue. These past events may have damaged charcoal canister and other EVAP components. Although, no DTC or issues with of fumes ever reported, since engine was installed.



"jab on the brakes fairly hard" "reverse and it starts to die again" If moment had anything to do with stall. It "may" point to a loose ground or wire block.

No fuel press when gas cap removed. The cooling a few minutes then starting, does point to fuel point "kind of". What would is if was hot day and you had just Thottle back form running at a higher RPM.


Condition/issue change for the worst, after a fuel pump install. First report of CEL.

Now that I’m thinking about it, didn’t you put new SAIS parts on this engine?

Radiator has some bugs in it of course but nothing alarming. I’ll give it a proper clean when I get to MI. Coolant in the radiator is too warm to check now, will do in the ayem.

Everything looks perfectly normal behind the fuel door. No pressure, no smells, no leaking, etc.

The fuel pump install went smoothly. O-ring is in, little rubber locating boot on the bottom is back on, etc. It was all very straight forward. On the first crank of the key it momentarily fired then died, second crank it lit right up. I drove it about 40-50 miles to camp that evening without issue. It wasn’t until the next morning when the CEL came on and the drivability problems started. I did keep the original pump just in case.

In any case, I’m still driving it. Just made it to Mitchell, SD. Low speeds/load is mildly annoying so I usually drop a gear at those times. It’s tolerable cruising at 70mph. Interestingly enough, the fuel economy hasn’t suffered.

 

[2001LC]

Oops, yeah I didn’t disconnect the battery. I’ve been through a few more tanks of 91 since then so maybe it’s good?


Now that I’m thinking about it, didn’t you put new SAIS parts on this engine?

Radiator has some bugs in it of course but nothing alarming. I’ll give it a proper clean when I get to MI. Coolant in the radiator is too warm to check now, will do in the ayem.

Everything looks perfectly normal behind the fuel door. No pressure, no smells, no leaking, etc.

The fuel pump install went smoothly. O-ring is in, little rubber locating boot on the bottom is back on, etc. It was all very straight forward. On the first crank of the key it momentarily fired then died, second crank it lit right up. I drove it about 40-50 miles to camp that evening without issue. It wasn’t until the next morning when the CEL came on and the drivability problems started. I did keep the original pump just in case.

In any case, I’m still driving it. Just made it to Mitchell, SD. Low speeds/load is mildly annoying so I usually drop a gear at those times. It’s tolerable cruising at 70mph. Interestingly enough, the fuel economy hasn’t suffered.

S.A.I pump (filter) was not new.

Coolant in radiator, should be checked after 8 hour cool down. Not just when cool enough to open cap. This should be done early in the AM, before sun warms the vehicle or air (coolant).

Let's hope it's just a bad MAF, or something simple like a loose/cut wire. That bank 1 misfire, was just related to the lean condition. Looking back at your screen shot of DTC. It appears only BK1 lean DTC was current. The other DTCs are under secondary. Which I'm reading as pending. Pending being DTC not tripped the 3 times required to kick off a CEL. Very likely as engine was stalling, it didn't run long enough to set off all as current and capture BK2 as misfiring at all.

Sound like no issue with install of fuel pump.

Good luck!

Interesting I had 2 emergence calls this weekend, with stalls while ascending mountain passes. Both 06-07, and both sound like fuel pump failing.
Perhaps it best if we just do these fuel pumps as a PM.

 

[GTV]

I am almost certain that when you hook up an OBD2 reader to your LC, it will give you a P0420/30 cat-related DTC.

Dude, you're 0/2!

I had to borrow my aunt's tablet but I finally got Techstream up and running.
Same as Autozone told me. P0171 and P0174, system too lean bank 1 and 2, respectively.
I apologize for the tiny font, I didn't have the patience to learn how to make it larger (or learn how to screenshot on her tablet). I was just happy to finally have TS again!

What here looks wrong, if anything?

 

[GTV]

I’m looking for anomalies in the patterns here but nothing is really standing out to me other than the Long FT B2S1 with a value of 3.9%

 

[jerryb]

I see nothing.

at idle you're not going to see anything- really it needs to be monitored under load, while it's happening.
if there was bad fuel, a random electrical anomaly- loss of spark, you can get a check engine light that comes and goes at will, even faintly lighting for a brief moment.

best thing would be to watch misfires live with a big load on the engine. I think you can watch misfire margin as a stand alone value.
But idk if BT apps can do that. Anyway, + is good in your example above.
+3.9 is nothing., FT. +35 bad, +15 not great, +/-10 fine.

 

[GTV]

I see nothing.

at idle you're not going to see anything- really it needs to be monitored under load, while it's happening.
if there was bad fuel, a random electrical anomaly- loss of spark, you can get a check engine light that comes and goes at will, even faintly lighting for a brief moment.

best thing would be to watch misfires live with a big load on the engine. I think you can watch misfire margin as a stand alone value.
But idk if BT apps can do that. Anyway, + is good in your example above.
+3.9 is nothing., FT. +35 bad, +15 not great, +/-10 fine.

Thank you for the input, that makes sense.

So probably the best/easiest way to watch for misfires is to have two people, a driver and passenger monitoring TS live, unless there's a way to record live data?

I think you can watch misfire margin as a stand alone value.

Could you please explain this in more detail?

 

[jerryb]

I read your whole thread again.
I'd try to log the two rear o2 sensor's voltages and look for spikes if I thought the front of one cat was caved in.

 

[jerryb]

I've done it alone on my phone.

it's a percentage of misfire possibility. A idle, the chance is low. I've never looked at mine at high load/high throttle, so I wouldn't know if it would actually get to zero. I've only had one misfire event with this car in 6 years or so.

I only pointed it out so that if you were driving and had that option to look at instead of trying to monitor 8 coils it might be a give away and easier with one person in the car.

Because of the lean codes I'd be more concerned about front and rear o2 sensor voltage than miscounts.

I'd take two trips, one watching o2 voltage (4) and then another watching misfire counts.

 

[GTV]

I've been attempting to monitor Techstream while my uncle drives but for some reason Techstream will not stay connected to the vehicle for more than a few moments at a time while underway. Furthermore, he can't really feel anything abnormal while driving and nor can I from the passenger seat. I'm not certain if there's still a subtle miss or it has somehow worked itself out. For now I cleared the codes and I'm moving on with life. I hate to leave this unsolved but if something crops up again I'll update this thread.

 

[GTV]

Since the last post I've driven from Southern Michigan to the U.P., back south through Ohio, Kentucky, Illinois, Missouri, Arkansas, Texas and now I'm finally back in New Mexico. Truck has performed flawlessly and while I'll never know with 100% confidence I've had a lot of seat time to think about what the issue(s) may have been.

2006-07 is known to have fuel pump issues. After I swapped the pump I have not had the same stalling problem. Hopefully it stays that way.

The air filter was really dirty, possibly causing a big restriction that resulted in drivability issues. I don't particularly want a snorkel but I don't want to pull air from the fender anymore either.

The tank that I dumped 3M fuel system cleaner in perfectly coincided with the CEL shutting itself off. I've always considered that stuff to be snake oil but maybe it did something. Drivability issues persisted but very gradually cleared up over the next 2,000ish miles.

In conclusion (knock on wood), I want to think the new fuel pump cured the stalling issue and the dirty filter caused my drivability issues that took a couple thousand miles for the ECU to relearn and work itself out. Time will tell.

Thank you to everyone who contributed to this thread.

 

[abuck99]

The fender drawn intake air is generally pretty clean unless you are following someone or a group closely on a dusty trail. The snorkel will reduce dust intake but I'm with you- dont care for the look. Spread out between trucks and bring a spare filter. Check often, knock the dust out.

 

[GTV]

The fender drawn intake air is generally pretty clean unless you are following someone or a group closely on a dusty trail. The snorkel will reduce dust intake but I'm with you- dont care for the look. Spread out between trucks and bring a spare filter. Check often, knock the dust out.

99% of the mileage I've done on dirt has been solo, I guess I just need to clean/change it more often. I don't hate the look of the TJM snorkel, it's much more minimal than most. I'd just have to come up with a solution for the antenna.